Multilayer Electrolyzer Stack Converts Carbon Dioxide to Gas Products at High Pressure with High Efficiency

Electrochemical reduction of CO₂ is a value-added approach to both decrease the atmospheric emission of carbon dioxide and form valuable chemicals. We present a zero gap electrolyzer cell, which continuously converts gas phase CO₂ to products without using any liquid catholyte. This is the first report of a multilayer CO₂ electrolyzer stack for scaling up the electrolysis process. CO formation with partial current densities above 250 mA cm⁻² were achieved routinely, which was further increased to 300 mA cm⁻² (with ∼95% faradic efficiency) by pressurizing the CO₂ inlet (up to 10 bar). Evenly distributing the CO₂ gas among the layers, the electrolyzer operates identically to the sum of multiple single-layer electrolyzer cells. When passing the CO₂ gas through the layers consecutively, the CO₂ conversion efficiency increased. The electrolyzer simultaneously provides high partial current density, low cell voltage (-3.0 V), high conversion efficiency (up to 40%), and high selectivity for CO production.